Tracking Saturday snowfall trends

The winds of change are blowing colder air into Minnesota.

Thursday began mild again with temperatures in the 30s across southern Minnesota. But gusty northwest winds are driving a colder Arctic air mass southward through Minnesota tonight. You can see the frosty hues of single-digit temperatures pooling in northern Minnesota on the Thursday afternoon temperature map.

Low temperatures will hover either side of zero across Minnesota Friday and Saturday morning. That cold air dome will play a role in generating snowfall for Minnesota Saturday.

Saturday storm system

A low-pressure system tracks from Colorado into Kansas Saturday. Southerly flow ahead of that system will pump milder air and moisture toward Minnesota. As moisture overruns the cold dome above Minnesota, snowfall will develop by Saturday morning in southwest Minnesota. The snow will spread east into the Twin Cities by early to mid-afternoon. The steadiest, heaviest snowfall favors Saturday night. Snow should end from west to east Sunday morning.

NOAA’s GFS model paints the snow moving east with the heaviest bands favoring areas from the southern Twin Cities to the Iowa border.

We call this “overrunning” snow in the weather business. It typically produces drier fluffier snowfall as colder air lingers at ground level. Snow to water ratios with this system appear to favor around 15:1. That will produce a fairly dry, powder snow compared to previous systems.

Heaviest snow south

The southerly storm track places southern Minnesota and northern Iowa in the favored zone for the heaviest snow.

The Canadian and European models favor lighter snow across northern Minnesota with most areas picking up 1 to 3 inches. The Twin Cities currently lies on the northern fringes of the heavier snowfall zone across southern Minnesota. That would suggest a general range of 2” north to as much as 6” in the southern Twin Cities. The heaviest snowfall zone favors southern Minnesota. That’s where a wide area of 4 to 8 inches is more likely.

Here’s the Canadian model snowfall output.

NOAA’s GFS model leans a little heavier than the European and Canadian models. It cranks out a wider area of 4 to 8-inch snowfall potential across southern Minnesota.

Bottom line: Expect snowfall to spread from west to east across Minnesota Saturday. The steadiest snow favors Saturday night. Travel will likely become slick Saturday afternoon through early Sunday morning.

Forecasts may still change. If the system goes any further south that would reduce snowfall in the Twin Cities which is currently riding the northern edge of the heavier snowfall zone.

Stay tuned as we track possible forecast model shifts through Friday.